A patient with respiratory distress and a distinct almond odor is encountered after exposure to an inhaled toxin. Which agent is most likely responsible?

A patient with respiratory distress and a distinct almond odor is encountered after exposure to an inhaled toxin. Which agent is most likely responsible?

• A. Arsenic
• B. Chlorine
• C. Cyanide
• D. Sarin

Answer: (C)

Cyanide is most likely. The almond-like odor is a classic clue associated with cyanide exposure, and inhalation of cyanide can rapidly disrupt cellular oxygen use. Cyanide inhibits cytochrome c oxidase in the mitochondria, so even though oxygen is present in the blood, cells can’t use it to produce energy. This leads to rapid respiratory distress and signs of tissue hypoxia, often with lactic acidosis. Chlorine would cause irritation and airway injury from a gas exposure, not an almond smell. Arsenic exposure has other classic toxic effects and doesn’t have that odor cue. Sarin is a nerve agent producing cholinergic symptoms, not specifically tied to almond odor.

Cyanide is most likely. The almond-like odor is a classic clue associated with cyanide exposure, and inhalation of cyanide can rapidly disrupt cellular oxygen use. Cyanide inhibits cytochrome c oxidase in the mitochondria, so even though oxygen is present in the blood, cells can’t use it to produce energy. This leads to rapid respiratory distress and signs of tissue hypoxia, often with lactic acidosis.

Chlorine would cause irritation and airway injury from a gas exposure, not an almond smell. Arsenic exposure has other classic toxic effects and doesn’t have that odor cue. Sarin is a nerve agent producing cholinergic symptoms, not specifically tied to almond odor.